Analysis of epidermal growth factor receptor gene expression in stained smears and formalin-fixed, paraffin-embedded...

Previous studies have demonstrated quantitation of epidermal growth factor receptors (EGFR) to be of prognostic significance in breast, bladder, esophageal and other neoplasms. However, the relatively large quantity of unfixed tissue required for epidermal growth factor radioligand binding assays (RLBA) has precluded its application to cytologic specimens and small biopsy specimens. For this reason we evaluated reverse transcription intron differential polymerase chain reaction (RTIDPCR) as an assay of EGFR gene expression. Squamous cell carcinoma (A431 and SiHa), transitional cell carcinoma (HT1376, T24, RT4), mammary (MCF7) and endocervical (HeLa) adenocarcinoma, and leukemia (K562) cell lines were used to compare RTIDPCR and RLBA. RTIDPCR involved reverse transcription of RNA and amplification of cDNA using primers for beta-actin and EGFR. Good agreement was observed between the RLBA and RTIDPCR results. RNA extracted from fresh cells, Diff-Quik-stained smears and formalin-fixed, paraffin-embedded cell pellet sections yielded similar results. These data suggest that RTIDPCR may be useful in evaluating gene expression by cells processed as cytologic specimens.